When a silver halide light-sensitive material is exposed to light including the light of a light-sensitive wavelength region for said light-sensitive material and developed, the photographic density or blackening density increases as the amount of exposure increases until it reaches a maximum value. When the amount of exposure is further increased, the photographic density begins to decrease to form, finally, a positive image. Such a phenomenon is generally called solarization. Also, in a silver halide emulsion which is optically or chemically fogged in the production step of the silver halide emulsion, a similar reversal phenomenon by light occurs. The direct positive silver halide photographic emulsion in this invention is the latter type photographic emulsion, that is, a photographic silver halide emulsion which is previously optically or chemically fogged so that the emulsion forms a positive image after ordinary light exposure and ordinary development.
A previously fogged direct positive silver halide photographic emulsion frequently cannot obtain a sufficiently low minimum density (e.g., a pure white portion is not obtained) with a conventional technique to reduce the contrast of images. Accordingly, sufficient image quality cannot be obtained.
In order to reduce the minimum density, a desensitizing compound is used. However, since conventional desensitizing compounds frequently reduce the maximum density simultaneously when they reduce the minimum density, the use of such conventional densensitizing compounds is frequently accompanied by a reduction in contrast and frequently causes an undesirable phenomenon for photographic image quality. In the field of graphic arts requiring particularly high contrast, the development of a photographic light-sensitive material which can reduce the reversal minimum density without reducing contrast has been strongly desired.